Cellulose ester manufacture



coagulated state.

Patented May 29, 1945 CELLULOSE ESTER MANUFACTURE Francis P. Alles, Wayncsboro, Va., asslgnor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application July 1, 1942, Serial No. 449,312

40mins. (01.117-144) This invention relates to the manufacture oi? cellulose organic ester structures having improved dyeing properties;- More particularlyit relates to the manufacture of wet coagulated cellulose organic ester structures which can be satisfactorily dyed with direct, acid and chrome dyes.

Generally speaking, cellulose organic esterv structures have no afllnity for direct dyes such as are commonly used for dyeing cotton and regenerated cellulose nor afllnity for acid or chrome dyes such as are commonly used for dyeing silk Preferably, the gel, wet-coagulated cellulose ori ganic ester structure is impregnated with a soluinvention.

and wool, unless they are chemically modified by suitable pretreatment. The only exception to this generalization is found in cellulose organic esters in a highly swollen state as may be produced by wet coagulation. Thus, gel, wet-spun cellulose acetate yam, i. e., cellulose acetate yarn whichhas been made by the wet spinning pro ess, andwhich is still in the freshly coagulate undried state, acceptsdirect dyes,-acid dyes, and

Y chrome dyes, However, structures in the gel state are inherently weal: and do not lend themselves conveniently to the usual textile operations such as twisting, winding, knitting, weaving or combing and carding, which precede dyeing. For thisreason it has not been possible heretofore to take advantage of the superior dyeing properties of this material in commercial practice.

An object of this invention, therefore, is to preserve in dry wet-coagulated cellulose organi'c ester structures, the dyeing properties which characterize such structures in the gel or wet, freshly Another object is to maintain the characteristic dye aminity of gel, wet-spun cellulose organic ester yarn through the drying step, whereby, on rewetting, the yarn may be dyed with acid, direct, and chrome dyes.

A still further object is to treat wet-spun cellulose acetate yarn in, the gel state in order to maintain its afllnity for acid, direct, and chrome dyes through the drying ste These and other objects will more clearly appear hereinafter.

."lhese objects are realized by my invention which, briefly stated, comprises impregnating gel, wet-coagulated cellulose'organic'ester structures with a solution of a bulk agent.

tion of a, bulk agent of sufllcient concentration to give to 400 parts by weight of solid per 100' parts of cellulose ester.

The following examples further illustrate myv Percentage compositions are by weight unless otherwis indicated.

Example I A solution consisting of 15% cellulose acetate (containing about 54.5% combined acetic acid), 5% water, and 80% acetic acid, was spun into a coagulating bath consisting of 12% acetic acid, 13.5% ammonium acetate, and 74.5% water, which coagulating bath was maintained at a temperature of 8.50 C. The filament bundle consisting \small skeins.

of 240 filaments of 20 denier each was washed free of acetic acid and wet reeled into a number of A'number of these skeins of gel yam were impregnated by immersion in an aqueous solution containing 4% by'vclume o1 glycerin and 27% by volume of commercial corn syrup sold by qornJE'roducts Refining Company der the name .of Karo, after which the s were wrung so as to retain about 1 part of non-volatile material per part, of cellulose acetate when airdried.

(b) Another impregnated and dried skein was rinsed thoroughly to remove all the corn syrup and glycerin and then dyed while still wet by immersion in a dye bath of du Pont Brilliant Milling Green B Cone; (Color Index No. 667) to a depth comparable tothat obtained by a corresponding dyeing 01- wool. Light-fastness nesswere excellent.

Example. II

A skeln of gel yam produced in accordance with Example I was impregnated with an aqueous soluand wash-fasttion of 10% (by volume). of commercial corn By the term bulk agent is meant any relative.-

' ly non-volatile impregnant which can fill the capillaries or spaces-between molecules or crystallites of theJcelluloSe ester and prevent substantial collapse of these cell walls on drying.

Preferred bulk agents are polyhydric alcohols such'as glycerin, sugar, com syrup, andth 'like.

. Be. anda purity of 61.5. The treated skein was syrup sold by -corn Products Reflning'company, under the name of "Two-Star corn syrup of 42 wrung so as to'retainabout 1 part of corn syrup solids per 3 parts of cellulose acetate after being dried at room temperature. This dried skein. of

yarn when immersed in a dye bath of du Pont Pontamine Fast Black L (Color Index No. 363) dyed to a deep black shade.

Example I]! 1.5 inch, 3 denier cellulose acetate staple pro- 5 duced from filament bundles spun substantially as described in Example I was.thorough1y'-impregnated with an'aqueous solution consisting of 28% Karo corn syrup and 5% glycerol. .The

' impregnated staplewas wrung so as to retain one part of nonvolatile impregnants per part of cellulose acetate after air drying at room temperature.

A wad of the dried staple was rinsed in water, wrung and then entered into an aqueous dye bath of-du PontPontachrome Black F (Color "Index No. 299) and dyed according to the usual procedure. The depth of dyeing observedwas equivalent to that obtained by a corresponding treatment ot wool. Light-fastness and washi'astness were excellent.

Example IV A skein oI--gel', wet-spun cellulose acetate yarn such as-described in Example I was impregnated with an aqueous solution of 15%. Gardinol WA,

(the sodium salt of the alcohol acid sulfate of a fraction of the alcohols obtainedby hydrogenatcoconut' oil, mainlysodium lauryl sulfate), wrimg out and air dried. The. dried skein :was thereafter-rinsed in water to remove the Gardinol and-dyed with Pontamine Fast Red 83L (Color Index No. 2'18) to produce a depth of dyeing equal to'that obtained in corresponding direct dyeing of. nesswere .excellent.

' lqkaample-lrf viscoserayon. Light-fastne'ss and wash-fastlikewise treated with good results.

In addition to the bulking agents described above, examples of satisfactory bulk agents are molasses, dextrine, dextrose, maltose, sucrose,

ethylene glycol,'diethyle!!1 e glycol, gelatin, casein,

albumin, polymethacry 0 acid, quebracho ex-' 1 tract, gum arabic, urea, inorganic saltsiand pectic acid salts. Any relatively non-volatile material that can be uniformly impregnated into the gel, wet-coagulatedcellulose organic ester structurecan be employed. Preferably these materials are water-soluble, for impregnation is most convenient from aqueous'solutions, since the struc- "ture to be impregnated is already highly swollen with water. However, other liquids, which are solvents for the bulk agents but not solvents for the cellulose ester and possessing relatively high vapor pressures, may be used as the vehicle for the bulk agent. Corn syrup is especially efiective as a bulk agent because it does not crystallize readily and; as water is removed from'the impregnated structure, the syrup-becomes increasin'gly more viscous until it ub'stantially a. solid,

but yet an amorphous high viscosity fluid.

A gel, wet spun cellulose acetate yarn was, im-

pregnated with .an aqueous solution containing 20% polyethylene oxide (1500 molecular weight) and wrung soas to retain about 1 part 01 polyethylene oxide per part of cellulose acetate and air dried. After rinsing in water to remove the polyethylene oxide, the-yarn was dyed with Pont-, amine Fast Red 8BL .(Color Index No. 2.78) Depth of dyeing was equivalent to that by similarly dyeing viscose rayon.

, I I f Esampze v1 A skein of gel, wet-spun cellulose acetate yarn was impregnated with an 80% aqueous solution of glycerol, wrung and air dried. The dried yarn,

was subsequently thoroughly rinsed in water to remove the glycerol Pontamine Sky Blue 63X (Color Index No. 518). The dyeing was equivalent ,to that of viscose rayon.

s Example VII obtained and then dyed with .du Pont'" Cellulose acetate yarn processed and dyed in accordance with this invention is unusually light fast and wash-fast, in some cases even more light and wash-fast than cellulose dyed with the same direct dye. Very probably the high degree of fastness is due to the fact that the dye penetrates to the very center of the fibers or filaments,

whereas the processes suggested heretofore to modify the dyeing'of cellulosederivative threads rendered only the surface of the yarn capable of accepting dye and had been merely'a surface dyeing eflect. Naturally, this kind of dyeing is much more susceptible to fading, either through washing or due to the action of sunlight.

,I claim: I

1. In the process of manufacturing cellulose acetate structures wherein the structures are formed in. a coagulating bath, the steps which A skein of gel, wet-spun cellulose acetate yarn was impregnated with an aqueous solut'ionconsisting of5% by volume of commercial corn syrup such as used in Example I: and 5% by weight of sodium chloride, wrimg and air dried." The resulting dried yarn was thoroughly rinsed in water to remove thebulking'agentand then dyed with du 'PontPontamine Fast Red 83L (Color Index No. 278). Good dyeing was obtained. K

It is to be understood, 1' course, that the above examples are merely for purposes .of illustration and that my inventionv is not limited ,to the mate'rials, agents and proportions therein recited but is. susceptible rather to wide variation. 1

, Thus, although scr'ibed in terms of treating gel, wet-spun celluthe acetone soluble variety lo'se acetate yarn of comprise impregnating the structures while still in the freshly coagulated gel state with corn syrup, and thereafter drying said structures.

2. In the process of manufacturing cellulose acetate structure's'wl'ierein the structures" are formed in a coagulating bath, the steps which comprise impregnating the structures while still a in the freshly coagulated gel state 'with corn syrup and glycerin, and thereafter drying-said structures, a 3. A dry cellulose acetate structure having substantially uncollapsed capillaries filled withfcorn syrup-and-exte'nding throughout the entire cross sectional area of the structure, said structure being capable of accepting direct, acid and chrome stantially uncollapsed. capillaries filled with cornsyrup and glycerin and extending throughout the r entire eross sectional area of the structure, said this invention has been as.

structure being capable of accepting direct, acid, I and chrome dyes.

"FRANCIS P. w

A dry cellulose seems structure having sub- 

